I think it's really important when people post write ups like this, that they discuss their level of experience and what their dominant shooting subjects are. This helps give us context. I find that people get flamed a great deal for offering opinions without context as others seem to accuse them of trying to be experts. Given context though, I think reviews like this are great and can be very valuable for beginners or intermediate shooters as it helps us form an opinion based partly on people's real world experience. Despite my complete disagreement with some statements regarding the 18-105 and the Sigma 10-20, I really like how the OP has offered a balanced assessment of these and other lenses. I really like how the OP also provides positive comments on certain lenses that they've tested, but haven't liked because they don't suit their particular shooting style. Kudos for not being narrow-minded.

So, thanks for the assessments. If you offered us some context, it might help us judge how your review compares to our shooting situations.